People can communicate anytime and anywhere via mobile terminals along with the constant development of communication technologies. Initially they communicate generally through making calls, sending short messages, etc. by using the mobile terminals over mobile communication networks deployed by mobile communications operators. Although subscribers can also access the Internet over such mobile communication networks to obtain information in a larger number of forms over the Internet, they have to pay a considerable fee for traffic arising from the access. Thus the Wi-Fi technology has been developed for solving this problem. Wi-Fi is a technology by which personal computers, handheld devices (e.g., a Personal Digital Assistant (PDA), a handset, etc.), and other terminals are connected wirelessly with each other, and a terminal device supporting Wi-Fi can access the Internet by using a wireless signal transmitted by a wireless signal transmitting device nearby without resorting to the mobile communication networks as long as the terminal device can receive the wireless signal.
The Wi-Fi technology undoubtedly has offered a technical basis for all kinds of online application software to be applied on mobile terminals, but a security risk may occur in a practical application. For example, a subscriber accessing Networks using a Wi-Fi signal source provided by a provider may find that his or her account registered in an instant message tool has been embezzled, etc. Consequently, how to improve the security in use of the Wi-Fi signal has become a technical problem to be necessarily addressed by those skilled in the art.